4 files changed, 429 insertions, 0 deletions
diff --git a/src/video_core/texture/etc1.cpp b/src/video_core/texture/etc1.cpp
new file mode 100644
index 000000000..af60cde1e
--- /dev/null
+++ b/src/video_core/texture/etc1.cpp
@@ -0,0 +1,124 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include "common/bit_field.h"
+#include "common/color.h"
+#include "common/common_types.h"
+#include "common/math_util.h"
+#include "common/vector_math.h"
+#include "video_core/texture/etc1.h"
+
+namespace Pica {
+namespace Texture {
+
+namespace {
+
+constexpr std::array<u8[2], 8> etc1_modifier_table = {{
+    {2, 8}, {5, 17}, {9, 29}, {13, 42}, {18, 60}, {24, 80}, {33, 106}, {47, 183},
+}};
+
+union ETC1Tile {
+    u64 raw;
+
+    // Each of these two is a collection of 16 bits (one per lookup value)
+    BitField<0, 16, u64> table_subindexes;
+    BitField<16, 16, u64> negation_flags;
+
+    unsigned GetTableSubIndex(unsigned index) const {
+        return (table_subindexes >> index) & 1;
+    }
+
+    bool GetNegationFlag(unsigned index) const {
+        return ((negation_flags >> index) & 1) == 1;
+    }
+
+    BitField<32, 1, u64> flip;
+    BitField<33, 1, u64> differential_mode;
+
+    BitField<34, 3, u64> table_index_2;
+    BitField<37, 3, u64> table_index_1;
+
+    union {
+        // delta value + base value
+        BitField<40, 3, s64> db;
+        BitField<43, 5, u64> b;
+
+        BitField<48, 3, s64> dg;
+        BitField<51, 5, u64> g;
+
+        BitField<56, 3, s64> dr;
+        BitField<59, 5, u64> r;
+    } differential;
+
+    union {
+        BitField<40, 4, u64> b2;
+        BitField<44, 4, u64> b1;
+
+        BitField<48, 4, u64> g2;
+        BitField<52, 4, u64> g1;
+
+        BitField<56, 4, u64> r2;
+        BitField<60, 4, u64> r1;
+    } separate;
+
+    const Math::Vec3<u8> GetRGB(unsigned int x, unsigned int y) const {
+        int texel = 4 * x + y;
+
+        if (flip)
+            std::swap(x, y);
+
+        // Lookup base value
+        Math::Vec3<int> ret;
+        if (differential_mode) {
+            ret.r() = static_cast<int>(differential.r);
+            ret.g() = static_cast<int>(differential.g);
+            ret.b() = static_cast<int>(differential.b);
+            if (x >= 2) {
+                ret.r() += static_cast<int>(differential.dr);
+                ret.g() += static_cast<int>(differential.dg);
+                ret.b() += static_cast<int>(differential.db);
+            }
+            ret.r() = Color::Convert5To8(ret.r());
+            ret.g() = Color::Convert5To8(ret.g());
+            ret.b() = Color::Convert5To8(ret.b());
+        } else {
+            if (x < 2) {
+                ret.r() = Color::Convert4To8(static_cast<u8>(separate.r1));
+                ret.g() = Color::Convert4To8(static_cast<u8>(separate.g1));
+                ret.b() = Color::Convert4To8(static_cast<u8>(separate.b1));
+            } else {
+                ret.r() = Color::Convert4To8(static_cast<u8>(separate.r2));
+                ret.g() = Color::Convert4To8(static_cast<u8>(separate.g2));
+                ret.b() = Color::Convert4To8(static_cast<u8>(separate.b2));
+            }
+        }
+
+        // Add modifier
+        unsigned table_index =
+            static_cast<int>((x < 2) ? table_index_1.Value() : table_index_2.Value());
+
+        int modifier = etc1_modifier_table[table_index][GetTableSubIndex(texel)];
+        if (GetNegationFlag(texel))
+            modifier *= -1;
+
+        ret.r() = MathUtil::Clamp(ret.r() + modifier, 0, 255);
+        ret.g() = MathUtil::Clamp(ret.g() + modifier, 0, 255);
+        ret.b() = MathUtil::Clamp(ret.b() + modifier, 0, 255);
+
+        return ret.Cast<u8>();
+    }
+};
+
+} // anonymous namespace
+
+Math::Vec3<u8> SampleETC1Subtile(u64 value, unsigned int x, unsigned int y) {
+    ETC1Tile tile{value};
+    return tile.GetRGB(x, y);
+}
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/etc1.h b/src/video_core/texture/etc1.h
new file mode 100644
index 000000000..e188b19df
--- /dev/null
+++ b/src/video_core/texture/etc1.h
@@ -0,0 +1,16 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+#include "common/vector_math.h"
+
+namespace Pica {
+namespace Texture {
+
+Math::Vec3<u8> SampleETC1Subtile(u64 value, unsigned int x, unsigned int y);
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/texture_decode.cpp b/src/video_core/texture/texture_decode.cpp
new file mode 100644
index 000000000..f611a1aa9
--- /dev/null
+++ b/src/video_core/texture/texture_decode.cpp
@@ -0,0 +1,229 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/assert.h"
+#include "common/color.h"
+#include "common/logging/log.h"
+#include "common/math_util.h"
+#include "common/swap.h"
+#include "common/vector_math.h"
+#include "video_core/pica.h"
+#include "video_core/texture/etc1.h"
+#include "video_core/texture/texture_decode.h"
+#include "video_core/utils.h"
+
+using TextureFormat = Pica::Regs::TextureFormat;
+
+namespace Pica {
+namespace Texture {
+
+constexpr size_t TILE_SIZE = 8 * 8;
+constexpr size_t ETC1_SUBTILES = 2 * 2;
+
+size_t CalculateTileSize(TextureFormat format) {
+    switch (format) {
+    case TextureFormat::RGBA8:
+        return 4 * TILE_SIZE;
+
+    case TextureFormat::RGB8:
+        return 3 * TILE_SIZE;
+
+    case TextureFormat::RGB5A1:
+    case TextureFormat::RGB565:
+    case TextureFormat::RGBA4:
+    case TextureFormat::IA8:
+    case TextureFormat::RG8:
+        return 2 * TILE_SIZE;
+
+    case TextureFormat::I8:
+    case TextureFormat::A8:
+    case TextureFormat::IA4:
+        return 1 * TILE_SIZE;
+
+    case TextureFormat::I4:
+    case TextureFormat::A4:
+        return TILE_SIZE / 2;
+
+    case TextureFormat::ETC1:
+        return ETC1_SUBTILES * 8;
+
+    case TextureFormat::ETC1A4:
+        return ETC1_SUBTILES * 16;
+
+    default: // placeholder for yet unknown formats
+        UNIMPLEMENTED();
+        return 0;
+    }
+}
+
+Math::Vec4<u8> LookupTexture(const u8* source, unsigned int x, unsigned int y,
+                             const TextureInfo& info, bool disable_alpha) {
+    // Coordinate in tiles
+    const unsigned int coarse_x = x / 8;
+    const unsigned int coarse_y = y / 8;
+
+    // Coordinate inside the tile
+    const unsigned int fine_x = x % 8;
+    const unsigned int fine_y = y % 8;
+
+    const u8* line = source + coarse_y * info.stride;
+    const u8* tile = line + coarse_x * CalculateTileSize(info.format);
+    return LookupTexelInTile(tile, fine_x, fine_y, info, disable_alpha);
+}
+
+Math::Vec4<u8> LookupTexelInTile(const u8* source, unsigned int x, unsigned int y,
+                                 const TextureInfo& info, bool disable_alpha) {
+    DEBUG_ASSERT(x < 8);
+    DEBUG_ASSERT(y < 8);
+
+    using VideoCore::MortonInterleave;
+
+    switch (info.format) {
+    case Regs::TextureFormat::RGBA8: {
+        auto res = Color::DecodeRGBA8(source + MortonInterleave(x, y) * 4);
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::RGB8: {
+        auto res = Color::DecodeRGB8(source + MortonInterleave(x, y) * 3);
+        return {res.r(), res.g(), res.b(), 255};
+    }
+
+    case Regs::TextureFormat::RGB5A1: {
+        auto res = Color::DecodeRGB5A1(source + MortonInterleave(x, y) * 2);
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::RGB565: {
+        auto res = Color::DecodeRGB565(source + MortonInterleave(x, y) * 2);
+        return {res.r(), res.g(), res.b(), 255};
+    }
+
+    case Regs::TextureFormat::RGBA4: {
+        auto res = Color::DecodeRGBA4(source + MortonInterleave(x, y) * 2);
+        return {res.r(), res.g(), res.b(), static_cast<u8>(disable_alpha ? 255 : res.a())};
+    }
+
+    case Regs::TextureFormat::IA8: {
+        const u8* source_ptr = source + MortonInterleave(x, y) * 2;
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return {source_ptr[1], source_ptr[0], 0, 255};
+        } else {
+            return {source_ptr[1], source_ptr[1], source_ptr[1], source_ptr[0]};
+        }
+    }
+
+    case Regs::TextureFormat::RG8: {
+        auto res = Color::DecodeRG8(source + MortonInterleave(x, y) * 2);
+        return {res.r(), res.g(), 0, 255};
+    }
+
+    case Regs::TextureFormat::I8: {
+        const u8* source_ptr = source + MortonInterleave(x, y);
+        return {*source_ptr, *source_ptr, *source_ptr, 255};
+    }
+
+    case Regs::TextureFormat::A8: {
+        const u8* source_ptr = source + MortonInterleave(x, y);
+
+        if (disable_alpha) {
+            return {*source_ptr, *source_ptr, *source_ptr, 255};
+        } else {
+            return {0, 0, 0, *source_ptr};
+        }
+    }
+
+    case Regs::TextureFormat::IA4: {
+        const u8* source_ptr = source + MortonInterleave(x, y);
+
+        u8 i = Color::Convert4To8(((*source_ptr) & 0xF0) >> 4);
+        u8 a = Color::Convert4To8((*source_ptr) & 0xF);
+
+        if (disable_alpha) {
+            // Show intensity as red, alpha as green
+            return {i, a, 0, 255};
+        } else {
+            return {i, i, i, a};
+        }
+    }
+
+    case Regs::TextureFormat::I4: {
+        u32 morton_offset = MortonInterleave(x, y);
+        const u8* source_ptr = source + morton_offset / 2;
+
+        u8 i = (morton_offset % 2) ? ((*source_ptr & 0xF0) >> 4) : (*source_ptr & 0xF);
+        i = Color::Convert4To8(i);
+
+        return {i, i, i, 255};
+    }
+
+    case Regs::TextureFormat::A4: {
+        u32 morton_offset = MortonInterleave(x, y);
+        const u8* source_ptr = source + morton_offset / 2;
+
+        u8 a = (morton_offset % 2) ? ((*source_ptr & 0xF0) >> 4) : (*source_ptr & 0xF);
+        a = Color::Convert4To8(a);
+
+        if (disable_alpha) {
+            return {a, a, a, 255};
+        } else {
+            return {0, 0, 0, a};
+        }
+    }
+
+    case Regs::TextureFormat::ETC1:
+    case Regs::TextureFormat::ETC1A4: {
+        bool has_alpha = (info.format == Regs::TextureFormat::ETC1A4);
+        size_t subtile_size = has_alpha ? 16 : 8;
+
+        // ETC1 further subdivides each 8x8 tile into four 4x4 subtiles
+        constexpr unsigned int subtile_width = 4;
+        constexpr unsigned int subtile_height = 4;
+
+        unsigned int subtile_index = (x / subtile_width) + 2 * (y / subtile_height);
+        x %= subtile_width;
+        y %= subtile_height;
+
+        const u8* subtile_ptr = source + subtile_index * subtile_size;
+
+        u8 alpha = 255;
+        if (has_alpha) {
+            u64_le packed_alpha;
+            memcpy(&packed_alpha, subtile_ptr, sizeof(u64));
+            subtile_ptr += sizeof(u64);
+
+            alpha = Color::Convert4To8((packed_alpha >> (4 * (x * subtile_width + y))) & 0xF);
+        }
+
+        u64_le subtile_data;
+        memcpy(&subtile_data, subtile_ptr, sizeof(u64));
+
+        return Math::MakeVec(SampleETC1Subtile(subtile_data, x, y),
+                             disable_alpha ? (u8)255 : alpha);
+    }
+
+    default:
+        LOG_ERROR(HW_GPU, "Unknown texture format: %x", (u32)info.format);
+        DEBUG_ASSERT(false);
+        return {};
+    }
+}
+
+TextureInfo TextureInfo::FromPicaRegister(const Regs::TextureConfig& config,
+                                          const Regs::TextureFormat& format) {
+    TextureInfo info;
+    info.physical_address = config.GetPhysicalAddress();
+    info.width = config.width;
+    info.height = config.height;
+    info.format = format;
+    info.SetDefaultStride();
+    return info;
+}
+
+} // namespace Texture
+} // namespace Pica
diff --git a/src/video_core/texture/texture_decode.h b/src/video_core/texture/texture_decode.h
new file mode 100644
index 000000000..5c636939a
--- /dev/null
+++ b/src/video_core/texture/texture_decode.h
@@ -0,0 +1,60 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+#include "common/vector_math.h"
+#include "video_core/pica.h"
+
+namespace Pica {
+namespace Texture {
+
+/// Returns the byte size of a 8*8 tile of the specified texture format.
+size_t CalculateTileSize(Pica::Regs::TextureFormat format);
+
+struct TextureInfo {
+    PAddr physical_address;
+    unsigned int width;
+    unsigned int height;
+    ptrdiff_t stride;
+    Pica::Regs::TextureFormat format;
+
+    static TextureInfo FromPicaRegister(const Pica::Regs::TextureConfig& config,
+                                        const Pica::Regs::TextureFormat& format);
+
+    /// Calculates stride from format and width, assuming that the entire texture is contiguous.
+    void SetDefaultStride() {
+        stride = Pica::Texture::CalculateTileSize(format) * (width / 8);
+    }
+};
+
+/**
+ * Lookup texel located at the given coordinates and return an RGBA vector of its color.
+ * @param source Source pointer to read data from
+ * @param x,y Texture coordinates to read from
+ * @param info TextureInfo object describing the texture setup
+ * @param disable_alpha This is used for debug widgets which use this method to display textures
+ * without providing a good way to visualize alpha by themselves. If true, this will return 255 for
+ * the alpha component, and either drop the information entirely or store it in an "unused" color
+ * channel.
+ * @todo Eventually we should get rid of the disable_alpha parameter.
+ */
+Math::Vec4<u8> LookupTexture(const u8* source, unsigned int x, unsigned int y,
+                             const TextureInfo& info, bool disable_alpha = false);
+
+/**
+ * Looks up a texel from a single 8x8 texture tile.
+ *
+ * @param source Pointer to the beginning of the tile.
+ * @param x, y In-tile coordinates to read from. Must be < 8.
+ * @param info TextureInfo describing the texture format.
+ * @param disable_alpha Used for debugging. Sets the result alpha to 255 and either discards the
+ *                      real alpha or inserts it in an otherwise unused channel.
+ */
+Math::Vec4<u8> LookupTexelInTile(const u8* source, unsigned int x, unsigned int y,
+                                 const TextureInfo& info, bool disable_alpha);
+
+} // namespace Texture
+} // namespace Pica